Title explains everything.
1: Classic/Withered Foxy did not cause The Bite Of 87, Mangle did. Before you say "Blah blah blah Book, blah blah blah Foxy did it, blah blah blah Game Theory says he did", may I remind you that he appears in FnaF 1, which, in the canon timeline, happens after FnaF 2? Also, why did the TOY Animatronics get scrapped, and not the Withered Animatronics? And furthermore, Mangle's name was a staff-given name, and not the actual name given to the animatronic. As Ralph, THE GUY WE "PLAY AS" in The Week Before states:
"But kids these days just can't keep their hands to themselves. The staff literally had to put Foxy back together during just every shift. So eventually they just stopped trying and left him in some kind of "take apart, put back together" attraction. Now he's just a mess of parts. I think the employees refer to him as just...the mangle."
The name Mangle only became the character's name long after the restaurant closed, so they're still, by the time of FnaF 2, named FOXY.
2: The Toy Animatronics are possessed by the kids William killed the day before Night 6.
Pretty self-evident.
3: Shadow Freddy and Bonnie are the ghosts of people who died in the Fredbear and Spring Bonnie suits, mentioned in FnaF 3, by Ralph
"After learning of an unfortunate incident at the sister location involving multiple and simultaneous springlock failures, the company has deemed the suits temporarily unfit for employees."
"Multiple and simultaneous" means both suits went off at the same time, most likely killing both employees.
